The invention relates to a device for forming stacks of sheet-like products, in particular of paper products, and to a method for stacking products.
A device of this type is disclosed, for example, in WO-A-02/22482. In the case of the device described therein, paper products coming from a high-speed printer are supplied in a continuous stream along a conveying direction to a transfer section and are set down on a horizontally oriented, rigid set-down table. The set-down table is lowered vertically during the stacking operation and is filled with the paper products until a stack has a required number of the paper products. The set-down table is then vertically lowered to a delivery section.
In the delivery section, a band conveyor reaches through a grid-like set-down table and transports the stack of paper products away. The set-down table, which is now empty, is moved back horizontally by a further band conveyor, counter to the conveying direction, and by more than a length of the set-down table. Then, the set-down table is transported horizontally upward by a further band conveyor into a holding-ready position.
As soon as the set-down table is required for receiving a new stack, a further band conveyor conveys the set-down table horizontally, parallel to the conveying direction, and into the delivery section. For an interruption-free formation of stacks, at least one further set-down table is guided in each case horizontally and vertically in the circuit-like table-circulating path.
EP-B-0737640 discloses a method and a device for inserting an auxiliary stack picking-up means in a sheet delivery unit of printing machines. In this case, with an uninterrupted supply of further sheets (paper products), an auxiliary stack frame is inserted over a main stack in a running direction of the sheets and synchronously with the movement of a paper product to be set down. The main stack can subsequently be removed, and then the auxiliary stack picking-up means withdrawn, so that the paper products can again be set down on a pallet (set-down table) of the main stack. As an alternative, the auxiliary stack picking-up means receives the new main stack. When the main stack, which has now come to rest on the auxiliary stack picking-up means, is transported away again, a further auxiliary stack picking-up means has to be brought up.